Reactor Damper for Passive Decay Heat Removal

Solution Overview

Problem

Existing nuclear reactor passive cooling systems, such as RVACS, result in significant power loss and material degradation due to constant heat removal, leading to economic inefficiency and structural issues like temperature gradients and vibration, which are not adequately addressed by current technologies.

Innovation Solution

A moveable damper system installed in coolant conduits that can restrict coolant flow during steady-state operations to minimize heat loss and induce flow when necessary, using passive mechanisms like gravity, electromagnets, or temperature-dependent switches to open during transient scenarios, ensuring efficient heat retention and emergency cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If constant heat removal is implemented through passive cooling systems, then reactor safety is improved, but thermodynamic efficiency deteriorates due to significant power loss

Engineering Contradiction:

Improvereactor safetyVSAvoidpower loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The damper is designed to be moveable between open and closed positions, allowing the cooling system to dynamically adjust its operation. During normal operation, the damper closes to minimize heat loss and maintain thermodynamic efficiency. During emergencies, the damper opens to enable maximum cooling capacity, thus resolving the contradiction between continuous safety and energy efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the flow rate parameter of coolant dynamically. By adjusting the damper position, the system transitions from high flow rate (open damper) for safety to low flow rate (closed damper) for efficiency, allowing operation at different points on the performance curve depending on reactor conditions.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If constant coolant flow is maintained, then cooling capacity is improved, but flow-induced vibrations increase causing material degradation

Engineering Contradiction:

Improvecooling capacityVSAvoidflow-induced vibrations

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

Instead of maintaining constant coolant flow, the system uses periodic opening and closing of the damper based on reactor conditions. This intermittent flow pattern reduces the cumulative vibrational stress on materials while still providing adequate cooling when the damper is open, resolving the contradiction between continuous cooling and vibration reduction.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The harmful continuous flow is extracted and replaced with intermittent flow. By removing the constant flow condition and replacing it with periodic flow controlled by the damper, the system eliminates the source of continuous vibrational stress while maintaining cooling capability when needed.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If passive cooling systems operate continuously, then heat removal reliability is improved, but economic efficiency deteriorates

Engineering Contradiction:

Improveheat removal reliabilityVSAvoideconomic efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The damper enables the cooling system to transition from continuous operation to conditional operation. By dynamically adjusting the damper position based on reactor conditions, the system maintains heat removal reliability when needed while improving economic efficiency by minimizing unnecessary cooling during normal operation.

Inventive Principle:

Principle #15Dynamics

4Loss of energy

If the damper remains closed during steady-state operation, then thermodynamic efficiency is improved, but cooling response during emergencies deteriorates

Engineering Contradiction:

Improveheat lossVSAvoidemergency cooling

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The damper is positioned in the closed state during steady-state operation to minimize heat loss and maximize thermodynamic efficiency. However, the system is designed with preliminary action mechanisms (temperature-dependent switches, gravity-assisted opening) that automatically open the damper when emergency conditions are detected, ensuring rapid response while maintaining efficiency during normal operation.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The damper system reduces heat loss and flow-induced vibrations, enhances thermodynamic efficiency, and ensures reliable coolant flow during accidents by controlling coolant flow, thereby addressing the inefficiencies and structural issues of existing passive cooling systems.

Implementation Method 1

A moveable damper system installed in coolant conduits that can restrict coolant flow during steady-state operations to minimize heat loss and induce flow when necessary, using passive mechanisms like gravity

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 2

A moveable damper system installed in coolant conduits that can restrict coolant flow during steady-state operations to minimize heat loss and induce flow when necessary, using passive mechanisms like gravity, electromagnets

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnet

Implementation Method 3

A moveable damper system installed in coolant conduits that can restrict coolant flow during steady-state operations to minimize heat loss and induce flow when necessary, using passive mechanisms like gravity, electromagnets, or temperature-dependent switches

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

The damper system reduces heat loss and flow-induced vibrations, enhances thermodynamic efficiency, and ensures reliable coolant flow during accidents by controlling coolant flow

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 5

The damper system reduces heat loss and flow-induced vibrations, enhances thermodynamic efficiency

Methodology Applied

Scientific EffectVibration damping: Damping

Data Source

PatentUS11380450B2Methods for airflow control in reactor passive decay heat removal using a damper

Publication Date: 2022.07.05 GE HITACHI NUCLEAR ENERGY AMERICAS LLC

AI summary

Damper systems selectively reduce coolant fluid flow in nuclear reactor passive cooling systems, including related RVACS. Systems include a damper that blocks the flow in a coolant conduit and is moveable to open, closed, and intermediate positions. The damper blocks the coolant flow when closed to prevent heat loss, vibration, and development of large temperature gradients, and the damper passively opens, to allow full coolant flow, at failure and in transient scenarios. The damper may be moveable by an attachment extending into the coolant channel that holds the damper in a closed position. When a transient occurs, the resulting loss of power and/or overheat causes the attachment to stop holding the damper, which may be driven by gravity, pressure, a spring, or other passive structure into the open position for full coolant flow. A power source and temperature-dependent switch may detect and stop holding the damper closed in such scenarios.